The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Additive manufacturing, e.g., laser deposition, electron beam deposition or freeform manufacturing is a process of joining materials layer upon layer, as opposed to subtractive manufacturing methodologies, such as milling away portions of a larger structure. For example, additive manufacturing is often used for constructing models, prototypes or other objects having intricate geometric designs from 3D model data. That is, such additive manufacturing is a process by which complicated structures can be fabricated in layers where each successive layer is deposited on top of the previous layer. However, in many additive techniques, the bonding of the independent layers is typically of a low structural quality, i.e., the structural integrity, strength and durability of the resulting part is not of high quality.
Additionally, in various instances, attempts have been made to use additive manufacturing to add material to an existing substrate, structure or part. However, neither the added material nor the joint where the material has been added to existing structure possess sufficiently high structural qualities. Hence, many additive manufacturing processes have failed for repairing, or adding to, other exiting structures because, among other reasons, the additive manufacturing process does not bond to the existing structure. Therefore, the resulting aggregate structure generally does not have the same structural quality as the original structure being repaired, or having material added.
Metal additive manufacturing, e.g., laser deposition and electron beam deposition, is an additive process using high energy source, in which metal is added to the part or product, layer by layer, to rapidly manufacture or form the part or product to a predetermined free-form shape. It is a technique that can produce 100% dense functional metal parts directly from a CAD system and eliminate the need for intermediate steps. The microstructure obtained through this process is dependent on the laser deposition parameters which include the laser power, laser scanning speed, the powder feed rate etc. While able to produce good bonding to the substrate, when the substrate or a part to be repaired material is of very fine grain microstructure, the high energy source may affect the quality of these fine grain structures due to high temperature operation. Therefore this becomes the limitation of these types of metal additive manufacturing (laser deposition and electron beam deposition).